This project has had me working a very complicated background prior to adding the particle tracks themselves. The two solid lines, coming from both the bottom and the right, are the two which collide. From the point of collision in the centre, I’ll be adding the resulting various curly tracks (of which three are already strongly or lightly indicated).
The upshot of this experiment has me looking back at the simplicity of #4 with some trepidation, wondering if a complicated background is really adequate. I’ll be finishing it, of course, and deciding then how the work relates aesthetically, before starting #6.